Network analyzer, network analyzing method, program, and recording medium

ABSTRACT

Errors of a measuring system are corrected by acquiring the phases of transmission tracking errors. A network analyzer includes a measuring system error factor recording unit which records measuring system error factors generated independently of frequency conversion carried out by a DUT, and an error factor acquiring unit which measures first coefficients and second coefficients of a correction mixer where a signal output from a terminal is a sum of a product of a signal input to the terminal and the first coefficient, and a product of a signal input to the other terminal and the second coefficient, and the ratio of magnitudes of the second coefficients is constant, and acquires the transmission tracking errors caused by the frequency conversion based on the measuring system error factors recorded in the measuring system error factor recording unit, the first coefficients, and the second coefficients.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 10/598,201,filed Oct. 5, 2006, now U.S. Pat. No. 7,561,987, which is the U.S.National Phase of International Application No. PCT/JP2005/002511, filedon Feb. 10, 2005.

TECHNICAL FIELD

The present invention relates to a network analyzer used to calculateand measure circuit parameters of a device under test.

BACKGROUND ART

There has conventionally been practiced measurement of circuitparameters (such as the S parameters) of a device under test (DUT). Adescription will now be given of the measurement method of the circuitparameters of a device under test (DUT) according to the prior art withreference to FIG. 25.

A signal at frequency f1 is transmitted from a signal source 110 to areceiving unit 120 via a DUT 200. The signal is received by thereceiving unit 120. It is assumed that the frequency of the signalreceived by the receiving unit 120 is f2. It is possible to acquire theS parameters and frequency characteristics of the DUT 200 by measuringthe signal received by the receiving unit 120.

On this occasion, measuring system errors are generated in themeasurement due to mismatching between a measuring system such as thesignal source 110 and the DUT 200, and the like. These measuring systemerrors include Ed: error caused by the direction of a bridge, Er: errorcaused by frequency tracking, and Es: error caused by source matching.FIG. 2G shows a signal flow graph relating to the signal source 110 ifthe frequency f1=f2. RF IN denotes a signal input from the signal source110 to the DUT 200 and the like, S11 m denotes an S parameter of the DUT200 and the like acquired based on a signal reflected from the DUT 200and the like, and S11 a denotes a true S parameter of the DUT 200 andthe like without the measuring system errors.

If the frequency f1=f2, the errors can be corrected in a mannerdescribed in a patent document 1 (Japanese Laid-Open Patent Publication(Kokai) No. H11-38054), for example. The correction in this way isreferred to as calibration. A brief description will now be given of thecalibration. A calibration kit is connected to the signal source 110 torealize three types of states: open circuit, short circuit, and load(standard load Z0). In these states, a signal reflected from thecalibration kit is acquired by a bridge to acquire three types of the Sparameter (S11 m) corresponding to the three types of states. The threetypes of variable Ed, Er, and Es are acquired from the three types ofthe S parameter.

However, the frequency f1 may not be equal to the frequency f2. Forexample, the DUT 200 may be a device providing a frequency conversionfunction such as a mixer. FIG. 27 shows a signal flow graph relating tothe signal source 110 if the frequency f1 is not equal to the frequencyf2. Though Ed and Es are the same as those of the case where thefrequency f1 and the frequency f2 are equal to each other, the Er isdivided into Er1 and Er2. Since the calibration as described in thepatent document 1 acquires only the three types of S parameter (S11 m),only Ed, Es, and Er1•Er2 can be acquired. Thus, Er1 and Er2 cannot beacquired.

Moreover, if the frequency f1 and the frequency f2 are not equal to eachother, measuring system errors due to the receiving unit 120 are notnegligible. FIG. 28 shows a signal flow graph if the signal source 110and the receiving unit 120 are directly connected with each other. S2 mdenotes an S parameter of the DUT 200 and the like acquired based on asignal received by the receiving unit 120. As shown in FIG. 28, thereare generated measuring system errors Et and EL caused by the receivingunit 120. These errors cannot be acquired by the calibration asdescribed in the patent document 1.

Therefore, if the frequency f1 is not equal to the frequency A2, theerrors are corrected as described in a patent document 2 (WO 031087856,Pamphlet). First, three types of calibration kits (open circuit, shortcircuit, and load (standard load Z0)) are connected to a signal source.This is the same as the method described in the patent document 1, andEd, Es, and Er1•Er2 can thus be acquired. The signal source is thenconnected to a power meter. Based on a result measured by the powermeter, Er1 and Er2 can be acquired (refer to FIG. 6 and FIG. 7 in thepatent document 2), Further, the signal source and a receiving unit aredirectly connected with each other, and Et and EL can be acquired basedon a measured result on this occasion (refer to FIG. 8 and FIG. 9 in thepatent document 2).

It should be noted that the transmission tracking error is defined asEr1•Et. According to the method described in the patent document 2, Er1and Et can be measured, and the transmission tracking error Er1•Et thuscan be acquired.

However, when the transmission tracking error Er1•Et is acquiredaccording to the method described in the patent document 2, it isnecessary to use a power meter to measure Er1. Since the power meter isused, it is not possible to acquire the phase of the transmissiontracking error.

An object of the present invention is to correct errors of a measuringsystem so as to acquire the phases of the transmission tracking errors.

DISCLOSURE OF THE INVENTION

According to the present invention, a network analyzer includes: ameasuring system error factor recording unit that records a measuringsystem error factor generated independently of a frequency conversion bya device under test; a correction coefficient output unit that outputsmeasured first coefficients and second coefficients of a correctionfrequency converting element wherein a signal output from one terminalis represented as a sum of a product of a signal input to the terminaland the first coefficient and a product of a signal input to the otherterminal and the second coefficient, and a ratio of the magnitudes ofthe second coefficients is constant; and a transmission tracking erroracquiring unit that acquires a transmission tracking error generated bythe frequency conversion based on the measuring system error factorrecorded in the measuring system error factor recording unit, and thefirst coefficients and the second coefficients output by the correctioncoefficient output unit.

According to the thus constructed invention, a measuring system errorfactor recording unit records a measuring system error factor generatedindependently of a frequency conversion by a device under test. Acorrection coefficient output unit outputs measured first coefficientsand second coefficients of a correction frequency converting elementwherein a signal output from one terminal is represented as a sum of aproduct of a signal input to the terminal and the first coefficient anda product of a signal input to the other terminal and the secondcoefficient, and a ratio of the magnitudes of the second coefficients isconstant. A transmission tracking error acquiring unit acquires atransmission tracking error generated by the frequency conversion basedon the measuring system error factor recorded in the measuring systemerror factor recording unit, and the first coefficients and the secondcoefficients output by the correction coefficient output unit.

According to the present invention, it is preferable that if the firstcoefficients are M11′ and M22′, the second coefficients are M12′ andM21′, a signal input to a first terminal is a1, a signal output from thefirst terminal is b1, a signal input to a second terminal is a2, and asignal output from the second terminal is b2 in the correction frequencyconverting element,

b1=M11′×a1+M12′×a2

b2=M21′×a1+M22′×a2, and

|M12′|/|M21′| is constant.

According to the present invention, it is preferable that the magnitudesof the second coefficients are the same for either of the terminals.

According to the present invention, it is preferable that the networkanalyzer further includes: an input signal measuring unit that measuresan input signal parameter relating to an input signal input to thedevice under test before the measuring system error factor is generated;a plurality of ports that are connected to a terminal of the deviceunder test, and output the input signal; and a device-under-test signalmeasuring unit that measures a device-under-test signal parameterrelating to a device-under-test signal input from the terminal of thedevice under test to the port.

According to the present invention, it is preferable that the correctioncoefficient output unit acquires the first coefficients and secondcoefficients of the correction frequency converting element according toa ratio of the input signal parameter measured by the input signalmeasuring unit and the device-under-test signal parameter measured bythe device-under-test signal measuring unit.

According to the present invention, it is preferable that thetransmission tracking error acquiring unit acquires the transmissiontracking error based on a ratio of error factors generated in a passagefrom the device-under-test signal being output from the terminal of thedevice under test without the frequency conversion to thedevice-under-test signal being received by the device-under-test signalmeasuring unit.

According to the present invention, a network analyzing method includes:a measuring system error factor recording step of recording a measuringsystem error factor generated independently of a frequency conversion bya device under test; a correction coefficient output step of outputtingmeasured first coefficients and second coefficients of a correctionfrequency converting element wherein a signal output from one terminalis represented as a sum of a product of a signal input to the terminaland the first coefficient and a product of a signal input to the otherterminal and the second coefficient, and a ratio of the magnitudes ofthe second coefficients is constant; and a transmission tracking erroracquiring step of acquiring a transmission tracking error generated bythe frequency conversion based on the measuring system error factorrecorded in the measuring system error factor recording step, and thefirst coefficients and the second coefficients output by the correctioncoefficient output step.

The present invention is a program of instructions for execution by thecomputer to perform a processing for analyzing a network. The processingincludes: a measuring system error factor recording step of recording ameasuring system error factor generated independently of a frequencyconversion by a device under test; a correction coefficient output stepof outputting measured first coefficients and second coefficients of acorrection frequency converting element wherein a signal output from oneterminal is represented as a sum of a product of a signal input to theterminal and the first coefficient and a product of a signal input tothe other terminal and the second coefficient, and a ratio of themagnitudes of the second coefficients is constant; and a transmissiontracking error acquiring step of acquiring a transmission tracking errorgenerated by the frequency conversion based on the measuring systemerror factor recorded in the measuring system error factor recordingstep, and the first coefficients and the second coefficients output bythe correction coefficient output step.

The present invention is a computer-readable medium having a program ofinstructions for execution by the computer to perform a processing foranalyzing a network. The processing includes: a measuring system errorfactor recording step of recording a measuring system error factorgenerated independently of a frequency conversion by a device undertest; a correction coefficient output step of outputting measured firstcoefficients and second coefficients of a correction frequencyconverting element wherein a signal output from one terminal isrepresented as a sum of a product of a signal input to the terminal andthe first coefficient and a product of a signal input to the otherterminal and the second coefficient, and a ratio of the magnitudes ofthe second coefficients is constant; and a transmission tracking erroracquiring step of acquiring a transmission tracking error generated bythe frequency conversion based on the measuring system error factorrecorded in the measuring system error factor recording step, and thefirst coefficients and the second coefficients output by the correctioncoefficient output step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a network analyzer1 according to an embodiment of the present invention;

FIG. 2( a) is a view showing a configuration of the DUT 2, and FIG. 2(b) shows a relationship among signals input to output from the firstterminal 2 a and the second terminal 2 b;

FIG. 3( a) shows a state (referred to as forward path) where the inputsignal (frequency f1) is supplied to the DUT 2 via the measuring unit 20(the terminal 14 a and the terminal 14 b are connected with each other),and FIG. 3( b) shows a state (referred to as reverse path) where theinput signal (frequency f2) is supplied to the DUT 2 via the measuringunit 30 (the terminal 14 a and the terminal 14 c are connected with eachother);

FIG. 4 is a functional block diagram showing a configuration of theforward path error factor acquiring unit 60;

FIG. 5 shows a state where the terminal 6 a of the calibration tool 6and the port 4 a are connected with each other;

FIG. 6 is a signal flow graph representing the state where thecalibration tool 6 is connected to the port 4 a;

FIG. 7 shows a state where the port 4 b is connected to the port 4 a;

FIG. 8 is a signal flow graph representing the state where the port 4 bis connected to the port 4 a;

FIG. 9 is a functional block diagram showing a configuration of thereverse path error factor acquiring unit 70;

FIG. 10 is a functional block diagram showing a configuration of theerror factor acquiring unit 90;

FIG. 11 is a diagram showing a calibration mixer 8 where the calibrationmixer 8 is connected to the network analyzer 1;

FIG. 12 is a functional block diagram showing a configuration of thecircuit parameter measuring unit 98;

FIG. 13 is a flowchart showing the operation of the embodiment of thepresent invention;

FIG. 14 is a flowchart showing a procedure to acquire the measuringsystem error factors (Ed, Er, Es, EL, and Et) of the network analyzer 1;

FIG. 15 is a flowchart showing a procedure to acquire the M parametersof the DUT 2;

FIG. 16 is a block diagram showing a configuration of a network analyzer1 according to a (first) variation;

FIG. 17 is a block diagram showing a configuration of a network analyzer1 according to a (second) variation;

FIG. 18 is a block diagram showing a configuration of the networkanalyzer 1 referred to prove an equation 1;

FIG. 19 is a signal flow graph representing a system of a FWD system ofthe network analyzer 1 shown in FIG. 18;

FIG. 20 is a signal flow graph representing a system of a REV system ofthe network analyzer 1 shown in FIG. 18;

FIG. 21 is a signal flow graph obtained by transforming the signal flowgraph shown in FIG. 19;

FIG. 22 is a signal flow graph obtained by transforming the signal flowgraph shown in FIG. 20;

FIG. 23 is a view showing error factors of a measuring system to whichthe signal flow graph shown in FIG. 21 corresponds;

FIG. 24 is a view showing error factors of a measuring system to whichthe signal flow graph shown in FIG. 22 corresponds;

FIG. 25 is a view showing a measurement method of the circuit parametersof a device under test (DUT) according to the prior art;

FIG. 26 shows a signal flow graph relating to the signal source 110 ifthe frequency f1=f2;

FIG. 27 shows a signal flow graph relating to the signal source 110 ifthe frequency f1 is not equal to the frequency f2; and

FIG, 28 shows a signal flow graph if the signal source 110 and thereceiving unit 120 are directly connected with each other.

BEST MODE FOR CARRYING OUT THE INVENTION

A description will now be given of an embodiment of the presentinvention with reference to drawings.

FIG. 1 is a block diagram showing a configuration of a network analyzer1 according to the embodiment of the present invention. To the networkanalyzer 1 is connected a DUT (Device Under Test) 2. The networkanalyzer 1 measures circuit parameters such as the S parameters of theDUT 2. It should be noted that if a mixer (multiplier) is used as theDUT 2, the S parameters are specifically referred to as M parameters.

FIG. 2( a) is a view showing a configuration of the DUT 2. The DUT 2 isa mixer (multiplier). The DUT 2 includes a first terminal 2 a, a secondterminal 2 b, an RF signal processing unit 2R, an IF signal processingunit 2I, and a local signal processing unit 2L.

If a signal a1 at a frequency f1 is input to the first terminal 2 a, thesignal is supplied to the RFI signal processing unit 2R. Moreover, tothe local signal processing unit 2L is supplied a local signal Lo(frequency fLo). The signal (frequency f1) supplied to the RF signalprocessing unit 2R and the signal (frequency fLo) supplied to the localsignal processing unit 2L are mixed, and a resulting signal is outputfrom the IF signal processing unit 2I via the second terminal 2 b as asignal b2 at a frequency f2 (=f1−fLo). If the signal a1 at the frequencyf1 is input from the first terminal 2 a, a certain portion of the signalis rejected without the frequency conversion by the DUT 2, and is outputfrom the first terminal 2 a as a signal b1 at the same frequency f1.

If a signal a2 at a frequency f2 is input to the second terminal 2 b,the signal is supplied to the IF signal processing unit 2I. Moreover, tothe local signal processing unit 2L is supplied the local signal Lo(frequency fLo). The signal (frequency f1) supplied to the RF signalprocessing unit 2R and the signal (frequency fLo) supplied to the localsignal processing unit 2L are mixed, and a resulting signal is outputfrom the RF signal processing unit 2R via the first terminal 2 a as asignal b1 at the frequency f1 (=f+fLo). If the signal a2 at thefrequency f2 is input from the second terminal 2 b, a certain portion ofthe signal is reflected without the frequency conversion by the DUT 2,and is output from the second terminal 2 b as a signal b2 at the samefrequency f2.

It should be noted that the signal a1 at the frequency f1 is denoted bya1(f1); the signal a2 at the frequency f2 is denoted by a2(f2); thesignal b1 at the frequency f1 is denoted by b1(f1), and the signal b2 atthe frequency f2 is denoted by b2(f2).

FIG. 2( b) shows a relationship among signals input to/output from thefirst terminal 2 a and the second terminal 2 b. Namely, there hold:

b1=M11×a1+M12×a2

b2=M21×a1+M22×a2.

It should be noted that M11 and M22 are referred to as firstcoefficients, and M12 and M21 are referred to as second coefficients.

With reference to FIG. 1 again, the network analyzer 1 includes ports 4a and 4 b, a DUT local signal port 4 c, a signal source 10, measuringunits 20 and 30, a DUT local signal oscillator 40, switches 52, 54, and56, a forward path error factor acquiring unit 60, and a reverse patherror factor acquiring unit 70, a measuring system error factorrecording unit 80, an error factor acquiring unit 90, and a circuitparameter measuring unit 98.

The port 4 a is connected to the measuring unit 20 and the firstterminal 2 a. The port 4 a outputs the input signal (frequency f1) fromthe signal source 10 to the first terminal 2 a.

The port 4 b is connected to the measuring unit 30 and the secondterminal 2 b. The port 4 b outputs the input signal frequency f2) fromthe signal source 10 to the second terminal 2 b.

The DUT local signal port 4 c is connected to the DUT local signaloscillator 40. The DUT local signal port 4 c supplies the DUT 2. with aDUT local signal from the DUT local signal oscillator 40.

The signal source 10 includes a signal output unit 12, a bridge 13, aswitch 14, an internal mixer 16, and a receiver (Rch) 18 (input signalmeasuring means).

The signal output unit 12 outputs the input signal at the frequency f1or f2.

The bridge 13 supplies the internal mixer 16 and the switch 14 with thesignal output from the signal output unit 12. The signal supplied by thebridge 13 is a signal which has not been influenced by measuring systemerror factors caused by the network analyzer 1.

The switch 14 includes terminals 14 a, 14 b, and 14 c. The terminal 14 ais connected to the bridge 13, and receives the signal from the bridge13. The terminal 14 b is connected to the measuring unit 20, and theterminal 14 c is connected to the measuring unit 30. The terminal 14 ais connected to the terminal 14 b or the terminal 14 c. If the terminal14 a and the terminal 14 b are connected with each other, the inputsignal output from the signal output unit 12 is supplied to themeasuring unit 20 (the frequency of the input signal on this occasion isf1). If the terminal 14 a and the terminal 14 c are connected with eachother, the input signal output from the signal output unit 12 issupplied to the measuring unit 30 (the frequency of the input signal onthis occasion is f2).

The internal mixer 16 mixes the signal supplied from the bridge 13 withan internal local signal, and outputs the mixed signal.

The receiver (Rch) 18 (input signal measuring means) measures the Sparameters of the signal output from the interval mixer 16. The receiver(Rch) 18 thus measures the S parameters relating to the input signalbefore there arises an influence of the measuring system error factorsdue to the network analyzer 1.

The measuring unit 20 includes a bridge 23, an internal mixer 26, and areceiver (Ach) 28 (device-under-test signal measuring means).

The bridge 23 outputs the signal supplied from the signal source 10 tothe port 4 a. Moreover, the bridge 23 receives a signal which has beenreflected back by the DUT 2, and a signal which has passed the DUT 2 viathe port 4 a, and supplies the internal mixer 26 with the receivedsignal. It should be noted that the signal which has been reflected bythe DUT 2, and the signal which has passed the DUT 2 are referred to asdevice-under-test signal.

The internal mixer 26 mixes the signal supplied from the bridge 23 withan internal local signal, and outputs the mixed signal.

The receiver (Ach) 28 (device-under-test signal measuring means)measures the S parameters of the signal output from the internal mixer26. The receiver (Ach) 28 thus measures the S parameters relating to thedevice-under-test signal.

The measuring unit 30 includes a bridge 33, an internal mixer 36, and areceiver (Bch) 38 (device-under-test signal measuring means).

The bridge 33 outputs the signal supplied from the signal source 10 tothe port 4 b. Moreover, the bridge 23 receives a signal which has beenreflected back by the DUT 2, and a signal which has passed the DUT 2 viathe port 4 b, and supplies the internal mixer 36 with the receivedsignals. It should be noted that the signal which has been reflected bythe DUT 2, and the signal which has passed the DUT 2 are referred to asdevice-under-test signal.

The internal mixer 36 mixes the signal supplied from the bridge 33 withan internal local signal, and outputs the mixed signal.

The receiver (Bch) 38 (device-under-test signal measuring means)measures the S parameters of the signal output from the internal mixer36. The receiver (Bch) 38 thus measures the S parameters relating to thedevice-under-test signal.

The DUT local signal oscillator 40 supplies the DUT 2 with the localsignal Lo (frequency fLo).

A signal flow graph representing the state shown in FIG. 1 is shown inFIG. 3. M11, M21, M12, and M22 are true M parameters (without theinfluence of the measuring system error factor) of the DUT 2.

FIG. 3( a) shows a state (referred to as forward path) where the inputsignal (frequency f1) is supplied to the DUT 2 via the measuring unit 20(the terminal 14 a and the terminal 14 b are connected with each other),and FIG. 3( b) shows a state (referred to as reverse path) where theinput signal (frequency f2) is supplied to the DUT 2 via the measuringunit 30 (the terminal 14 a and the terminal 14 c are connected with eachother).

The measuring system error factors for the forward path (refer to FIG.3( a)) include Ed1 (error caused by the direction of the bridge), Ei1,Eo1 (error caused by the frequency tracking), Es1 (error caused by thesource matching), Eg2, and EL2.

The measuring system error factors for the reverse path (refer to FIG.3( b)) include Ed2 (error caused by the direction of the bridge), Ei2,Eo2 (error caused by the frequency tracking), Es2 (error caused by thesource matching), Eg1, and EL1.

The switch 52 supplies any one of the forward path error factoracquiring unit 60, the error factor acquiring unit 90, and the circuitparameter measuring unit 98 with the measured result by the receiver(Ach) 28.

The switch 54 supplies any one of the reverse path error factoracquiring unit 70, the error factor acquiring unit 90, and the circuitparameter measuring unit 98 with the measured result by the receiver(Bch) 38.

The switch 56 supplies any one of the forward path error factoracquiring unit 60, the reverse path error factor acquiring unit 70, theerror factor acquiring unit 90, and the circuit parameter measuring unit98 with the measured result by the receiver (Rch) 18.

The forward path error acquiring unit 60 receives the measured result bythe receiver (Ach) 28 via the switch 52. Moreover, the forward patherror acquiring unit 60 receives the measured result by the receiver(Rch) 18 via the switch 56. The forward path error acquiring unit 60acquires Ed1, Ei1•Eo1 (=Er1), Es1, and EL2 for the reverse path (referto FIG. 3( a)) based on the measured result by the receiver (Ach) 28 andthe measured result by the receiver (Rch) 18.

FIG. 4 is a functional block diagram showing a configuration of theforward path error factor acquiring unit 60. The forward path errorfactor acquiring unit 60 includes a switch 62, a first forward patherror factor acquiring unit 64, and a second forward path error factoracquiring unit 66.

The switch 62 transmits the measured result by the receiver (Ach) 28 andthe measured result by the receiver (Rch) 18 to the first forward patherror factor acquiring unit 64 or the second forward path error factoracquiring unit 66. Specifically if a calibration tool 6 (describedlater) is connected to the port 4 a, the switch 62 transmits themeasured result by the receiver (Ach) 28 and the measured result by thereceiver (Rch) 18 to the first forward path error factor acquiring unit64. If the port 4 b is connected to the port 4 a, the switch 62transmits the measured result by the receiver (Ach) 28 and the measuredresult by the receiver (Rch) 18 to the second forward path error factoracquiring unit 66.

The first forward path error factor acquiring unit 64 acquires Ed1, Ei1,Ei1•Eo1 (=Er1), and Es1. FIG. 5 shows a state where the terminal 6 a ofthe calibration tool 6 and the port 4 a are connected with each other.The calibration tools 6 are well-known calibration tools which realizethree types of state: open circuit, short circuit, and load (standardload Z0) as described in Japanese Laid-Open Patent Publication (Kokai)No. H11-38054 (patent document 1).

A signal flow graph representing the state where the calibration tool 6is connected to the port 4 a is shown in FIG. 6. In FIG, 6, the measuredresult by the receiver (Rch) 18 is R1 (f1), and the measured result bythe receiver (Ach) 28 is A1 (f1). A relationship between R1(f1) andA1(f1) is represented by the following equation.

$\begin{matrix}{\left\lbrack {{EQU}.\mspace{14mu} 1} \right\rbrack {\frac{A\; 1\left( {f\; 1} \right)}{R\; 1\left( {f\; 1} \right)} = {{{Ed}\; 1} + \frac{{Er}\; {1 \cdot X}}{1 - {{Es}\; {1 \cdot X}}}}}} & \;\end{matrix}$

On this occasion, since three types of the calibration tool 6 are to beconnected, there are acquired three types of the combination of R1(f1)and A1(f1). As a result, obtained variables are three types of variable:Ed1, Ei1•Eo1 (=Er1), and Es1.

The second forward path error factor acquiring unit 66 receives Ed1,Ei1•Eo1 (=Er1), and Es1 from the first forward path error factoracquiring unit 64, and receives the measured result by the receiver(Ach) 28 and the measured result by the receiver (Rch) 18 via the switch62. The second forward path error factor acquiring unit 66 then acquiresEL2.

FIG. 7 shows a state where the port 4 b is connected to the port 4 a. Asignal flow graph representing the state where the port 4 b is connectedto the port 4 a is shown in FIG. 8. In FIG. 7, the measured result bythe receiver (Rch) 18 is R1 (f1), and the measured result by thereceiver (Ach) 28 is A1 (E1). It is assumed that the input signal(frequency f1) is output from the port 4 a via the measuring unit 20. Arelationship between R1(f1) and A1(f1) is represented by the followingequation.

$\begin{matrix}{\left\lbrack {{EQU}.\mspace{14mu} 2} \right\rbrack {\frac{A\; 1\left( {f\; 1} \right)}{R\; 1\left( {f\; 1} \right)} = {{{Ed}\; 1} + \frac{{Er}\; {1 \cdot {EL}}\; 2}{1 - {{Es}\; {1 \cdot {EL}}\; 2}}}}} & \;\end{matrix}$

On this occasion, Ed1, Er1, and Es1 are known, and EL2 can thus beacquired. The second forward path error factor acquiring unit 66 outputsEd1, Ei1•Eo1 (=Er1), Es1, and EL2 to the measuring system error factorrecording unit 80.

The reverse path error factor acquiring unit 70 receives the measuredresult by the receiver (Bch) 38 via the switch 54. Moreover, the reversepath error factor acquiring unit 70 receives the measured result by thereceiver (Rch) 18 via the switch 56. The reverse path error factoracquiring unit 70 acquires Ed2, Ei2•Eo2 (=Er2), Es2, and EL1 for thereverse path (refer to FIG. 3( b)) based on the measured result by thereceiver (Bch) 38 and the measured result by the receiver (Rch) 18.

FIG. 9 is a functional block diagram showing a configuration of thereverse path error factor acquiring unit 70. The reverse path errorfactor acquiring unit 70 includes a switch 72, a first reverse patherror factor acquiring unit 74, and a second reverse path error factoracquiring unit 76.

The switch 72 transmits the measured result by the receiver (Bch) 38 andthe measured result by the receiver (Rch) 18 to the first reverse patherror factor acquiring unit 74 or the second reverse path error factoracquiring unit 76. Specifically, if the calibration tool 6 is connectedto the port 4 b, the switch 72 transmits the measured result by thereceiver (Bch) 38 and the measured result by the receiver (Ech) 18 tothe first reverse path error factor acquiring unit 74. If the port 4 bis connected to the port 4 a, the switch 72 transmits the measuredresult by the receiver (Bch) 38 and the measured result by the receiver(Rch) 18 to the second reverse path error factor acquiring unit 76.

The first reverse path error factor acquiring unit 74 acquires Ed2, Ei2,and Ei2•Eo2 (=Er2), and Es2. The calibration tool 6 is described before,and a detailed description thereof, therefore, is omitted. On thisoccasion, if the measured result by the receiver (Rch) 18 is R2(f2), andthe measured result by the receiver (Bch) 38 is B2(f2), a relationshipbetween R2(f2) and B2(f2) is represented by the following equation.

$\begin{matrix}{\left\lbrack {{EQU}.\mspace{14mu} 3} \right\rbrack {\frac{B\; 2\left( {f\; 2} \right)}{R\; 2\left( {f\; 2} \right)} = {{{Ed}\; 2} + \frac{{Er}\; {2 \cdot X}}{1 - {{Es}\; {2 \cdot X}}}}}} & \;\end{matrix}$

On this occasion, since three types of the calibration tool 6 are to beconnected, there are acquired three types of the combination of R2(f2)and B2(f2). As a result, the acquired variables are three types ofvariable: Ed2, Ei2•Eo2 (=Er2), and Es2.

The second reverse path error factor acquiring unit 76 receives Ed2,Ei2•Eo2 (Er2), and Es2 from the first reverse path error factoracquiring unit 74, and receives the measured result of the receiver(Bch) 38 and the measured result of the receiver (Rch) 18 via the switch72. The second reverse path error factor acquiring unit 76 then acquiresEL1.

On this occasion, if the measured result by the receiver (Rch) 18 isAx), and the measured result by the receiver (Bch) 38 is B2(f2), arelationship between R2(f2) and B2(f2) is represented by the followingequation. It is assumed that the input signal (frequency f2) is outputfrom the port 4 b via the measuring unit 30.

$\begin{matrix}{\left\lbrack {{EQU}.\mspace{14mu} 4} \right\rbrack {\frac{B\; 2\left( {f\; 2} \right)}{R\; 2\left( {f\; 2} \right)} = {{{Ed}\; 2} + \frac{{Er}\; {2 \cdot {EL}}\; 1}{1 - {{{Es2} \cdot {EL}}\; 1}}}}} & \;\end{matrix}$

On this occasion, Ed2, Er2, and Es2 are known, and EL1 can thus beacquired The second reverse path error factor acquiring unit 76 outputsEd2, Ei2•Eo2 (=Er2), Es2, and EL1 to the measuring system error factorrecording unit 80.

The measuring system error factor recording unit 80 receives and recordsEd1, Ei1•Eo1 (=Er1), Es1, and EL2 from the forward path error factoracquiring unit 60, and Ed2, Ei2•Eo2 (=Er2), Es2, and EL1 from thereverse path error factor acquiring unit 70. Ed1, Er1, Es1, EL2, Ed2,Er2, Es2, and EL1 are the measuring system error factors generatedindependently of the frequency conversion by the device under test.

The error factor acquiring unit 90 acquires the transmission trackingerrors generated by the frequency conversion. It should be noted thatthe transmission tracking errors Et21 and Et12 are respectively definedas Et21=Ei1•Eg2 and Et12=Ei2•Eg1. The transmission tracking error is ameasuring system error factor generated by the frequency conversion bythe device under test.

Moreover, on acquiring the transmission tracking errors, a calibrationmixer 8 is connected to the network analyzer 1 as shown in FIG. 11. Thecalibration mixer 8 is approximately the same as the DUT 2. However, itshould be noted that if the first coefficients are M11′ and M22′, andthe second coefficients are M12′ and M21′, the ratio |M12′| to |M21′| isconstant, and if a bidirectional mixer is used as the calibration mixer8, |M12′|=|M21′|.

To this calibration mixer 8 is supplied the input signal (frequency f1)via the measuring unit 20, and is then supplied the input signalfrequency f2) via the measuring unit 30, and the transmission trackingerrors are acquired based on the measured result by the receiver (Rch)18, the measured result by the receiver (Ach) 28, and the measuredresult by the receiver (Bch) 38.

FIG. 10 is a functional block diagram showing a configuration of theerror factor acquiring unit 90. The error factor acquiring unit 90includes a measuring system error factor reading out unit 910, a switch922, a forward path measured data acquiring unit 924, a reverse pathmeasured data acquiring unit 926, a circuit parameter acquiring unit(calibration coefficient output means) 928, and a transmission trackingerror acquiring unit 930.

The measuring system error factor reading out unit 910 reads out Ed1,Er1, Es1, EL2, Ed2, Er2, Es2, and EL1 from the measuring system errorfactor recording unit 80, and outputs them to the transmission trackingerror acquiring unit 930.

The switch 922 transmits the measured result by the receiver (Rch) 18,the measured result by the receiver (Ach) 28, and the measured result bythe receiver (Bch) 38 to the forward path measured data acquiring unit924 or the reverse path measured data acquiring unit 926. Specifically,if the input signal (frequency f1) is supplied via the measuring unit 20(the terminal 14 a and the terminal 14 b are connected with each other),the measured result is transmitted to the forward path measured dataacquiring unit 924. If the input signal (frequency 2) is supplied viathe measuring unit 30 (the terminal 14 a and the terminal 14 c areconnected with each other), the measured result is transmitted to thereverse path measured data acquiring unit 926.

The forward path measured data acquiring unit 924 outputs the measuredresult by the receiver (Rch) 18, the measured result by the receiver(Ach) 28, and the measured result by the receiver (Bch) 38 received fromthe switch 922 respectively as R1(f1), A1(f1), and B1(f2) to the circuitparameter acquiring unit 928.

The reverse path measured data acquiring unit 926 outputs the measuredresult by the receiver (Rch) 18, the measured result by the receiver(Ach) 28, and the measured result by the receiver (Bch) 38 received fromthe switch 922 respectively as R2(f2), A2(f1), and B2(f2) to the circuitparameter acquiring unit 928.

The circuit parameter acquiring unit (calibration coefficient outputmeans) 928 acquires the M parameters of the calibration mixer 8 based onthe R1(f1), A1(f1), and B1(f2) received from the forward path measureddata acquiring unit 924, and R2(f2), A(f1), and B2(f2) received from thereverse path measured data acquiring unit 926.

If the M parameters acquired by the circuit parameter acquiring unit 928are denoted by M11 m′, M12 m′, M21 m′, and M22 m′,

M11 m′=A1(f1)/R1(f1),

M12 m′=A2(f1)/R2(f2),

M21 m′=B1(f2)/R1(f1), and

M22 m′=B2(f2)/R2(f2).

The transmission tracking error acquiring unit 930 receives the Mparameters: M11 m′, M12 m′, M21 m′, and M22 m′, of the calibration mixer8 acquired by the circuit parameter acquiring unit 928, and Ed1, Er1,Es1, EL2, Ed2, Er2, Es2, and EL1 read out by the measuring system errorfactor reading out unit 910, thereby acquiring the transmission trackingerrors Et21 and Et12.

First, detailed analysis of the network analyzer 1 reveals that thereexists a relationship represented by the following equation (1). Theproof thereof will be given later Moreover, the capital L included in“EL1” and “EL2” is denoted by “1”.

$\begin{matrix}\left\lbrack {{EQU}.\mspace{14mu} 5} \right\rbrack & \; \\{{{Eg}_{1} = {\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Er}_{1}}}} \right){Eo}_{1}}}{{Eg}_{2} = {\left( {1 - {{Ed}_{2}\frac{{Es}_{2} - {El}_{2}}{{Er}_{2}}}} \right){Eo}_{2}}}} & \left( {{equation}\mspace{14mu} 1} \right)\end{matrix}$

If there is designated as: X=Eo2/Eo1, the transmission tracking errorsEt21 and Et12 are represented by the following equation 2. Moreover, thecapital L included in “EL1” and “EL2” is denoted by “1”.

$\begin{matrix}\left\lbrack {{EQU}.\mspace{14mu} 6} \right\rbrack & \; \\{{{El}_{21} = {{Er}_{1}{X\left( {1 - {{Ed}_{2}\frac{{Es}_{2} - {El}_{2}}{{Er}_{2}}}} \right)}}}{{El}_{12} = {{Er}_{2}\frac{1}{X}\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Er}_{1}}}} \right)}}} & \left( {{equation}\mspace{14mu} 2} \right)\end{matrix}$

Eo1 is an error factor generated in a passage from the device-undertestsignal being output from the first terminal 2 a of the DUT 2 without thefrequency conversion to the device-under-test signal being received bythe receiver (Ach) 28. Eo2 is an error factor generated in a passagefrom the device-under-test signal being output from the second terminal2 b of the DUT 2 without the frequency conversion to thedevice-under-test signal being received by the receiver (Bch) 38.

As Ed1, Er1, Es1, EL1, Ed2, Er2, Es2, and EL2, those read out by themeasuring system error factor reading out unit 910 can be used. Thus, ifX is known, it is possible to acquire transmission tracking errors Et21and Et12.

On this occasion, there holds a relationship as expressed by thefollowing equation 3 between the M parameters: M11′, M12′, M21′, andM22′ of the calibration mixer 8 and the measured results of the Mparameters: M11 m′, M12 m′, M21 m′, and M22 m′ acquired by the circuitparameter acquiring unit 928. It should be noted that “′” (prime) suchas one used in “M11′” is omitted, and “M11′” is thus denoted by “M11”,for example. Moreover, the capital L included in “EL1” and “EL2” isdenoted by “1”.

$\begin{matrix}\left\lbrack {{EQU}.\mspace{14mu} 7} \right\rbrack & \; \\{\begin{pmatrix}M_{11} & M_{12} \\M_{21} & M_{22}\end{pmatrix} = {\begin{pmatrix}\frac{M_{11m} - {Ed}_{1}}{{Er}_{1}} & \frac{M_{12m}}{{El}_{12}} \\\frac{M_{21m}}{{El}_{21}} & \frac{M_{22m} - {Ed}_{2}}{{Er}_{2}}\end{pmatrix}\begin{pmatrix}{1 + {{Es}_{1}\frac{M_{11m} - {Ed}_{1}}{{Er}_{1}}}} & {{El}_{1}\frac{M_{12m}}{{El}_{12}}} \\{{El}_{2}\frac{M_{21m}}{{El}_{21}}} & {1 + {{Es}_{2}\frac{M_{22m} - {Ed}_{2}}{{Er}_{2}}}}\end{pmatrix}^{- 1}}} & \left( {{equation}\mspace{14mu} 3} \right)\end{matrix}$

By applying the equation 2 to the equation 3, M21′/M12′ is acquired asexpressed by the following equation 4. It should be noted that “′”(prime) such as one used in “M11′” is omitted, and “M11′” is thusdenoted by “M11”, for example. Moreover, the capital L included in “EL1”and “EL2” is denoted by “1”.

$\begin{matrix}\left\lbrack {{EQU}.\mspace{14mu} 8} \right\rbrack & \; \\{\frac{M_{21}}{M_{12}} = {\frac{1}{X^{2}} \cdot \frac{\begin{matrix}{M_{21m}\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Er}_{1}}}} \right)} \\\left\lbrack {{Er}_{2} + {\left( {M_{22m} - {Ed}_{2}} \right)\left( {{Es}_{2} - {El}_{2}} \right)}} \right\rbrack\end{matrix}}{\begin{matrix}{M_{12m}\left( {1 - {{Ed}_{2}\frac{{Es}_{2} - {El}_{2}}{{Er}_{2}}}} \right)} \\\left\lbrack {{Er}_{1} + {\left( {M_{11m} - {Ed}_{1}} \right)\left( {{Es}_{1} - {El}_{1}} \right)}} \right\rbrack\end{matrix}}}} & \left( {{equation}\mspace{14mu} 4} \right)\end{matrix}$

On this occasion, |M12′|=|M21′|, and there thus holds M12′=M21′×e^(θ).It should be noted that θ is a constant determined by the phase of thelocal signal Lo. The equation 4 is solved for X, and the followingequation 5 is consequently acquired. It should be noted that “′” (prime)such as one used in “M11′” is omitted, and “M11′” is thus denoted by“M11”, for example. Moreover, the capital L included in “EL1” and “EL2”is denoted by “1”.

$\begin{matrix}\left\lbrack {{EQU}.\mspace{14mu} 9} \right\rbrack & \; \\{X = {^{\frac{\theta}{2}}\sqrt{\frac{\begin{matrix}{M_{21m}\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Er}_{1}}}} \right)} \\\left\lbrack {{Er}_{2} + {\left( {M_{22m} - {Ed}_{2}} \right)\left( {{Es}_{2} - {El}_{2}} \right)}} \right\rbrack\end{matrix}}{\begin{matrix}{M_{12m}\left( {1 - {{Ed}_{2}\frac{{Es}_{2} - {El}_{2}}{{Er}_{2}}}} \right)} \\\left\lbrack {{Er}_{1} + {\left( {M_{11m} - {Ed}_{1}} \right)\left( {{Es}_{1} - {El}_{1}} \right)}} \right\rbrack\end{matrix}}}}} & \left( {{equation}\mspace{14mu} 5} \right)\end{matrix}$

It should be noted that it is possible to acquire θ in the equation 5while an arbitrary time point in a period during which the forward patherror factor acquiring unit 60 or the reverse path error factoracquiring unit 70 is acquiring the measuring system error factors isdesignated as a reference, and θ at this reference time point isdesignated as 0.

Consequently, X is acquired based on Ed1, Er1, Es1, EL1, Ed2, Er2, Es2,and EL2 recorded in the measuring system error factor recording unit 80,and the M parameters: M11 m′, M12 m′, M21 m′, and M22 m′ of thecalibration mixer 8 acquired by the circuit parameter acquiring unit(calibration coefficient output means) 928 (equation 5), and thetransmission tracking errors Et21 and Et12 are acquired based on X(equation 2).

The circuit parameter measuring unit 98 acquires the true M parametersof the DUT 2. The true M parameters imply M parameters from which theinfluence of the error factors is eliminated.

Moreover, when the true M parameters of the DUT 2 are acquired, the DUT2 is connected to the network analyzer 1 as shown in FIG. 1. To the DUT2 is supplied the input signal (frequency f1) via the measuring unit 20,and is then supplied the input signal (frequency f2) via the measuringunit 30, and the true M parameters of the DUT 2 are acquired based onthe measured result by the receiver (Rch) 18, the measured result by thereceiver (Ach) 28 and the measured result by the receiver (Bch) 38.

FIG. 12 is a functional block diagram showing a configuration of thecircuit parameter measuring unit 98. The circuit parameter measuringunit 98 includes a measuring system error factor reading out unit 980, aswitch 982, a forward path measured data acquiring unit 984, a reversepath measured data acquiring unit 986, a circuit parameter acquiringunit 988, and a true-value circuit parameter acquiring unit 989.

The measuring system error factor reading out unit 980 reads out Ed1,Er1, Es1, EL2, Ed2, Er2, Es2, and EL1 from the measuring system errorfactor recording unit 80, and outputs them to the true-value circuitparameter acquiring unit 989.

The switch 982 transmits the measured result by the receiver (Rch) 18,the measured result by the receiver (Ach) 28, and the measured result bythe receiver (Bch) 38 to the forward path measured data acquiring unit984, or the reverse path measured data acquiring unit 986. Specifically,if the input signal (frequency f1) is supplied via the measuring unit 20(the terminal 14 a and the terminal 14 b are connected with each other),the measured result is transmitted to the forward path measured dataacquiring unit 984. If the input signal (frequency f2) is supplied viathe measuring unit 30 (the terminal 14 a and the terminal 14 c areconnected with each other), the measured result is transmitted to thereverse path measured data acquiring unit 986.

The forward path measured data acquiring unit 984 outputs the measuredresult by the receiver (Rch) 18, the measured result by the receiver(Ach) 28, and the measured result by the receiver (Bch) 38 received fromthe switch 982 respectively as R1(f1), A1(f1), and B1(f2) to the circuitparameter acquiring unit 988.

The reverse path measured data acquiring unit 986 outputs the measuredresult by the receiver (Rch) 18, the measured result by the receiver(Ach) 28, and the measured result by the receiver (Bch) 38 received fromthe switch 982 respectively as R2(f2), A2(f1), and B2(f2) to the circuitparameter acquiring unit 988.

The circuit parameter acquiring unit 988 acquires the M parameters ofthe DUT 2 based on R1(f1), A1(f1), and B1(f2) received from the forwardpath measured data acquiring unit 984, and R2(f2), A2(f1) and B2(f2)received from the reverse path measured data acquiring unit 986.

If the M parameters acquired by the circuit parameter acquiring unit 988are M11 m, M12 m, M21 m, and M22 m,

M11 m=A1(f1)/R1(f1),

M12 m=A2(f1)/R2(f2),

M21 m=B1(f2)/R1(f1), and

M22 m=B2(f2)/R22).

The true value circuit parameter acquiring unit 989 receives the Mparameters: M11 m, M12 m, M21 m, and M22 m of the DUT 2 acquired by thecircuit parameter acquiring unit 988, Ed1, Er1, Es1, EL2, ES, Er2, Es2,and EL1 read out by the measuring system error factor reading out unit980, and the transmission tracking errors Et21 and Et12 acquired by theerror factor acquiring unit 90, and then acquires the true M parameters:M11, M12, M21, and M22 of the DUT 2.

The true M parameters M11, M12, M21, and M22 of the DUT 2 can beacquired according to the equation 3.

A description will now be given of an operation of the embodiment of thepresent invention. FIG. 13 is a flowchart showing the operation of theembodiment of the present invention.

First, the measuring system error factors (Ed, Er, Es, EL, and Et) ofthe network analyzer 1 are acquired (S10). It should be noted that Edcomprehensively represents Ed1 and Ed2; Er comprehensively representsEr1 and Er2; Es comprehensively represents Es1 and Es2; ELcomprehensively represents EL1 and EL2; and Et comprehensivelyrepresents Et21 and Et12.

The DUT 2 is connected to the network analyzer 1, and the M parametersof the DUT 2 are measured (820).

FIG. 14 is a flowchart showing a procedure to acquire the measuringsystem error factors (Ed, Er, Es, EL, and Et) of the network analyzer 1.

First, the calibration tool 6 is used to measure Ed, Er, and Es (S102).

In more detail, the three types (open circuit, short circuit, and load(standard load Z0)) of the calibration tool 6 are first connected to theport 4 a. On this occasion, the measured result by the receiver (Ach) 28and the measured result by the receiver (Rch) 18 are supplied to thefirst forward path error factor acquiring unit 64 via the switch 62 Thefirst forward path error factor acquiring unit 64 acquires Ed1, Er1, andEs1.

The three types (open circuit, short circuit, and load (standard loadZ0)) of the calibration tool 6 are then connected to the port 4 b. Onthis occasion, the measured result by the receiver (Bch) 38, and themeasured result by the receiver (Rch) 18 are supplied to the firstreverse path error factor acquiring unit 74 via the switch 72. The firstreverse path error factor acquiring unit 74 acquires Ed2, Er2, and Es2.

The port 4 a and the port 4 b are then directly connected with eachother, and EL is then measured (S104).

In more detail, the input signal (frequency f1) is output from the port4 a via the measuring unit 20. On this occasion, the measured result bythe receiver (Ach) 28 and the measured result by the receiver (Rch) 18are supplied to the second forward path error factor acquiring unit 66via the switch 62. The second forward path error factor acquiring unit66 acquires EL2. The second forward path error factor acquiring unit 66outputs Ed1, Er1, Es1, and EL2 to the measuring system error factorrecording unit 80.

The input signal (frequency f2) is then output from the port 4 b via themeasuring unit 30. On this occasion, the measured result by the receiver(Bch) 38 and the measured result by the receiver (Rch) 18 are suppliedto the second reverse path error factor acquiring unit 76 via the switch72. The second reverse path error factor acquiring unit 76 acquires EL1.The second reverse path error factor acquiring unit 76 outputs Ed2, Er2,Es2, and EL1 to the measuring system error factor recording unit 80.

The calibration mixer 8 is then connected to the network analyzer 1, andR, A, and B are measured (S106). It should be noted that Rcomprehensively represents R1(f1) and R2(f); A comprehensivelyrepresents A1(f1) and A2(f1); and B comprehensively represents B1(f2)and B2(f2).

In more detail, the input signal (frequency f1) is supplied via themeasuring unit 20. On this occasion, the measured result by the receiver(Rch) 18, the measured result by the receiver (Ach) 28, and the measuredresult by the receiver (Bch) 38 are supplied to the forward pathmeasured data acquiring unit 924 via the switch 922. The forward pathmeasured data acquiring unit 924 outputs R1(f1), A1(f1), and B1(f2) tothe circuit parameter acquiring unit 928.

The input signal (frequency 2) is then supplied via the measuring unit30. On this occasion, the measured result by the receiver (Rch) 18, themeasured result by the receiver (Ach) 28, and the measured result by thereceiver (Bch) 38 are supplied to the reverse path measured dataacquiring unit 926 via the switch 922. The reverse path measured dataacquiring unit 926 outputs R2(f2), A2(f1), and B2(f2) to the circuitparameter acquiring unit 928.

The circuit parameter acquiring unit 928 acquires the M parameters: M11m′, M12 m′, M21 m′, and M22 m′ of the calibration mixer 8.

The transmission tracking error acquiring unit 930 finally receives theM parameters: M11 m′, M12 m′, M21 m′, and M22 m′, of the calibrationmixer 8 acquired by the circuit parameter acquiring unit 928, and Ed1,Er1, Es1, EL2, Ed2, Er2, Es2, and EL1 read out by the measuring systemerror factor reading out unit 910, thereby acquiring transmissiontracking errors Et21 and Et12 (S108).

Specifically, the transmission tracking errors Et21 and Et12 areacquired by acquiring X according to the equation 5, and assigning X tothe equation 2.

FIG. 15 is a flowchart showing a procedure to acquire the M parametersof the DUT 2.

The DUT 2 is first connected to the network analyzer 1 and R, A, and Bare measured (S202).

In more detail, the input signal (frequency f1) is supplied via themeasuring unit 20. On this occasion, the measured result by the receiver(Rch) 18, the measured result by the receiver (Ach) 28, and the measuredresult by the receiver (Bch) 38 are supplied to the forward pathmeasured data acquiring unit 984 via the switch 982. The forward pathmeasured data acquiring unit 984 outputs R1(f1), A1(f1), and B1(f2) tothe circuit parameter acquiring unit 988.

The input signal (frequency f2) is supplied via the measuring unit 30.On this occasion, the measured result by the receiver (Rch) 18, themeasured result by the receiver (Ach) 28, and the measured result by thereceiver (Bch) 38 are supplied to the reverse path measured dataacquiring unit 986 via the switch 982. The reverse path measured dataacquiring unit 986 outputs R2(f2), A2(f1), and B2(f2) to the circuitparameter acquiring unit 988.

The circuit parameter acquiring unit 988 then determines the Mparameters: M11 m, M12 m, M21 m, and M22 m of the DUT 2 (S204).

The true value circuit parameter acquiring unit 989 finally receives theM parameters: M11 m, M12 m, M21 m, and M22 m of the DUT 2 acquired bythe circuit parameter acquiring unit 988, Ed1, Er1, Es1, EL2, Ed2, Er2,Es2, and EL1 read out by the measuring system error factor reading outunit 980, and the transmission tracking errors: Et21 and Et12 acquiredby the error factor acquiring unit 90, and then acquires the true Mparameters: M11, M12, M21, and M22 of the DUT 2 (S206).

According to the present embodiment, in order to acquire thetransmission tracking errors Et21 and. Et12, there are carried out theprocesses for acquiring the phase: (1) the calibration tool 6 isconnected to the port 4 a, and, then, the calibration tool 6 isconnected to the port 4 b, (2) the port 4 a and the port 4 b aredirectly connected with each other, and (3) the calibration mixer 8 isconnected to the port 4 a and port 4 b, the phases of the transmissiontracking errors can be acquired, and the errors of the measuring systemcan be corrected.

It should be noted that, according to the embodiment of the presentinvention, there is described the case where the network analyzer 1outputs the input signal, and there are provided two ports (ports 4 aand 4 b) used to receive the device-under-test signals from the DUT 2.However, there may be three or more of these ports.

For example, as shown in FIG. 16, there may be ports 4 d and 4 e inaddition to the ports 4 a and 4 b. A (first) variation shown in FIG. 16has such a configuration that the ports 4 d and 4 e, terminals 14 d and14 e of the switch 14, bridges 123 and 133, internal mixers 126 and 136,a receiver (Dch) 128 (device-under-test signal measuring means), and areceiver (Cch) 138 (device-under-test signal measuring means) are addedto the network analyzer 1. The other parts remain as described above. Itshould be noted that, for the sake of illustration, in FIG. 16 are notshown the DUT local signal oscillator 40, the switches 52, 54, and 56,the forward path error factor acquiring unit 60, the reverse path errorfactor acquiring unit 70, the measuring system error factor recordingunit 80, the error factor acquiring unit 90, and the circuit parametermeasuring unit 98.

The terminals 14 d and 14 e of the switch 14 are connected to thebridges 133-and 123.

The bridges 123 and 133 output the signal supplied by the signal source10 respectively to the ports 4 e and 4 d. Moreover, the bridges 123 and133 receive a signal which has been reflected back by the device undertest, and a signal which has passed the device under test respectivelyvia the port 4 e and 4 d, and supply respectively the internal mixers126 and 136 with the received signals.

The internal mixers 126 and 136 mix the signal supplied respectivelyfrom the bridges 123 and 133 with an internal local signal, andrespectively output the mixed signal.

The receiver (Dch) 128 and the receiver (Cch) 138 respectively measurethe S parameters of the signal output from the internal mixers 126 and136.

For example, as show in FIG. 17, there may be ports 4 d and 4 e inaddition to the ports 4 a and 4 b. A (second) variation shown in FIG. 17has such a configuration that from the (first) variation shown in FIG.16 are removed the bridge 13, the internal mixer 16, and the receiver(Rch) 18, and there are added bridges 13 b, 13 c, 13 d, and 13 e,internal mixers 16 b, 16 c, 16 d, and 16 e, receivers (Ech) 18 b, 18 e,18 d, and 18 e in place of them. It should be noted that, for the sakeof illustration, in FIG. 17 are not shown the DUT local signaloscillator 40, the switches 52, 54, and 56, the forward path errorfactor acquiring unit 60, the reverse path error factor acquiring unit70, the measuring system error factor recording unit 80, the errorfactor acquiring unit 90, and the circuit parameter measuring unit 98.

The terminals 14 b, 14 c, 14 d, and 14 e of the switch 14 arerespectively connected to the bridges 13 b, 13 c, 13 d, and 13 e.

The bridges 13 b, 13 c, 13 d, and 13 e respectively output a signalsupplied from the signal source 10 to the ports 4 a, 4 b, 4 d, and 4 evia the bridges 23, 33, 133, and 123. Moreover, the bridges 23, 33, 133,and 123 receive a signal which has been reflected back by the deviceunder test and a signal which has passed the device under testrespectively via the ports 4 a, 4 b, 4 d and 4 e, and suppliedrespectively the internal mixers 16 b, 16 c, 16 d, and 16 e with thereceived signals.

The internal mixers 16 b, 16 c, 16 d, and 16 e mix the signal suppliedby the bridges 13 b, 13 c, 18 d, and 13 e with an internal local signal,and output the mixed signals.

The receiver (Rch) 18 b, 18 c, 18 d, and 18 e respectively measure the Sparameters of the signal output from the internal mixers 16 b, 16 c, 16d, and 16 e.

According to the (second) variation shown in FIG. 17, there holdEs1=EL1, Es2=EL2, . . . , and the measurement and arithmetic operationare thus become easier.

Moreover, the above-described embodiment may be realized in thefollowing manner. Namely, a computer is provided with a CPU, a harddisk, and a media (such as a floppy disk (registered trade mark) and aCD-ROM) reader, and the media reader is caused to read a mediumrecording a program realizing the above-described respective parts (suchas the forward path error factor acquiring unit 60, the reverse patherror factor acquiring unit 70, the measuring system error factorrecording unit 80, and the error factor acquiring unit 90), therebyinstalling the program on the hard disk. This method may also realizethe above-described embodiments.

[Proof of Equation 1]

A path from SG1 to Port 1 is divided into blocks A, B, and C as shown inFIG. 18. If the SW is switched between 1: an FWD side (the signal isoutput), and 2: an REV side (the signal is not output), only the stateof the C block changes.

On this occasion, if:

the reflection coefficient and the transmission coefficient of the Ablock are Ax and Ay,

the S parameters of the B block: are Bij (i, j=1, 2, 3),

the reflection coefficient and the transmission coefficient of the Cblock if the SW is on “1: FWD side” are Cx and Cy, and

the reflection coefficient of the C block if the SW is on “2: REV side”is Cz,

an FWD system is represented by a signal flow graph shown in FIG. 19,and an REV system is represented by a signal flow graph shown in FIG.20.

On this occasion, there are considered only dependencies of the detectedvalues by the receivers and the signals at the Port 1, namely,

R1(f1), A1(f1), A2(f1), a1(f1), b1(f1), a1″(f1), and b1″(f1),

by summarizing the variables, the signal flow graph shown in FIG. 19 istransformed into one in FIG, 21, and the signal flow graph shown in FIG.20 is transformed into one in FIG. 22.

Though P11, P21, P12, P22, Qx, and Qy are respectively functions of Bij(i, j=1, 2, 3), Ax, and Ay, equations which describe these functions arenot used in subsequent calculation, and are thus not explicitlydescribed.

The signal flow graph shown in FIG. 21 corresponds to the error factorsof the measuring system shown in FIG. 23. The signal flow graph shown inFIG. 22 corresponds to the error factors of the measuring system shownin FIG. 24.

Therefore, the correspondences are represented by the followingequations.

$\begin{matrix}{\left\lbrack {{EQU}.\mspace{14mu} 10} \right\rbrack {{FWD}\text{:}}{{Ed}_{1} = {{Cy}\frac{1}{1 - {P_{11}{Cx}}}{Qx}}}{{Es}_{1} = {P_{22} + {P_{12}\frac{Cx}{1 - {P_{11}{Cx}}}P_{21}}}}{{Ei}_{1} = {{Cy}\frac{1}{1 - {P_{11}{Cx}}}P_{21}}}{{Eo}_{1} = {{Qy} + {P_{12}\frac{Cx}{1 - {P_{11}{Cx}}}{Qx}}}}{{REV}\text{:}}{{El}_{1} = {P_{22} + {P_{12}\frac{Cz}{1 - {P_{11}{Cz}}}P_{21}}}}{{Eg}_{1} = {{Qy} + {P_{12}\frac{Cz}{1 - {P_{11}{Cz}}}{Qx}}}}} & \;\end{matrix}$

The equations are thus calculated as follows.

$\begin{matrix}{{\left\lbrack {{EQU}.\mspace{14mu} 11} \right\rbrack {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Ei}_{1}}} = {\ldots = {P_{12}{Qx}\frac{{Cx} - {Cz}}{\left( {1 - {P_{11}{Cx}}} \right)\left( {1 - {P_{11}{Cz}}} \right)}}}}{{{{Eo}_{1} - {Eg}_{1}}==\ldots} = {{{P_{12}{Qx}\frac{{Cx} - {Cz}}{\left( {1 - {P_{11}{Cx}}} \right)\left( {1 - {P_{11}{Cz}}} \right)}}\therefore{{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Ei}_{1}}}} = {{Eo}_{1} - {Eg}_{1}}}}{{\begin{matrix}{\left. \Leftrightarrow{Eg}_{1} \right. = {{Eo}_{1} - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Ei}_{1}}}}} \\{= {\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Ei}_{1}{Eo}_{1}}}} \right){Eo}_{1}}} \\{= {\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {Ei}_{1}}{{Er}_{1}}}} \right){Eo}_{1}}}\end{matrix}\therefore{Eg}_{1}} = {\left( {1 - {{Ed}_{1}\frac{{Es}_{1} - {El}_{1}}{{Er}_{1}}}} \right){Eo}_{1}}}} & \;\end{matrix}$

[End of Proof of Equation 1]

1. A network analyzer comprising: a measuring system error factorrecorder that records a measuring system error factor generatedindependently of a frequency conversion by a device under test; acorrection coefficient outputter that outputs measured firstcoefficients and second coefficients of a correction frequencyconverting element wherein a signal output from one terminal isrepresented as a sum of a product of a signal input to the terminal andthe first coefficient and a product of a signal input to the otherterminal and the second coefficient, and a ratio of the magnitudes ofthe second coefficients is constant; and a transmission tracking erroracquirer that acquires a transmission tracking error generated by thefrequency conversion based on the measuring system error factor recordedin said measuring system error factor recorder, and the firstcoefficients and the second coefficients output by said correctioncoefficient outputter.
 2. The network analyzer according to claim 1,wherein if the first coefficients are M11′ and M22′, the secondcoefficients are M12′ and M21′, a signal input to a first terminal isa1, a signal output from the first terminal is b1, a signal input to asecond terminal is a2, and a signal output from the second terminal isb2 in said correction frequency converting element,b1=M11′×a1+M12′×a2b2=M21′×a1+M22′×a2, and|M12′|/|M21′| is constant.
 3. The network analyzer according to claim 1,wherein the magnitudes of the second coefficients are the same foreither of the terminals.
 4. The network analyzer according to claim 1comprising: an input signal measurer that measures an input signalparameter relating to an input signal input to the device under testbefore the measuring system error factor is generated; a plurality ofports that are connected to a terminal of the device under test, andoutput the input signal; and a device-under-test signal measurer thatmeasures a device-under-test signal parameter relating to adevice-under-test signal input from the terminal of the device undertest to said port.
 5. The network analyzer according to claim 4, whereinsaid correction coefficient outputter acquires the first coefficientsand second coefficients of said correction frequency converting elementaccording to a ratio of the input signal parameter measured by saidinput signal measurer and the device-under-test signal parametermeasured by said device-under-test signal measurer.
 6. The networkanalyzer according to claim 4, wherein said transmission tracking erroracquirer acquires the transmission tracking error based on a ratio oferror factors generated in a passage from the device-under-test signalbeing output from the terminal of the device under test without thefrequency conversion to the device-under-test signal being received bysaid device-under-test signal measurer.
 7. A network analyzing methodcomprising: recording a measuring system error factor generatedindependently of a frequency conversion by a device under test;outputting measured first coefficients and second coefficients of acorrection frequency converting element wherein a signal output from oneterminal is represented as a sum of a product of a signal input to theterminal and the first coefficient and a product of a signal input tothe other terminal and the second coefficient, and a ratio of themagnitudes of the second coefficients is constant; and acquiring atransmission tracking error generated by the frequency conversion basedon the measuring system error factor, and the first coefficients and thesecond coefficients.
 8. A program of instructions for execution by thecomputer to perform a processing for analyzing a network, saidprocessing comprising; recording a measuring system error factorgenerated independently of a frequency conversion by a device undertest; outputting measured first coefficients and second coefficients ofa correction frequency converting element wherein a signal output fromone terminal is represented as a sum of a product of a signal input tothe terminal and the first coefficient and a product of a signal inputto the other terminal and the second coefficient, and a ratio of themagnitudes of the second coefficients is constant; and acquiring atransmission tracking error generated by the frequency conversion basedon the measuring system error factor and the first coefficients and thesecond coefficients.
 9. A computer-readable medium having a program ofinstructions for execution by the computer to perform a processing foranalyzing a network, said processing comprising: recording a measuringsystem error factor generated independently of a frequency conversion bya device under test; outputting measured first coefficients and secondcoefficients of a correction frequency converting element wherein asignal output from one terminal is represented as a sum of a product ofa signal input to the terminal and the first coefficient and a productof a signal input to the other terminal and the second coefficient, anda ratio of the magnitudes of the second coefficients is constant; andacquiring a transmission tracking error generated by the frequencyconversion based on the measuring system error factor and the firstcoefficients and the second coefficients.
 10. The network analyzeraccording to claim 2, wherein the magnitudes of the second coefficientsare the same for either of the terminals.
 11. The network analyzeraccording to claim 2 comprising: an input signal measurer that measuresan input signal parameter relating to an input signal input to thedevice under test before the measuring system error factor is generated;a plurality of ports that are connected to a terminal of the deviceunder test, and output the input signal; and a device-under-test signalmeasurer that measures a device-under-test signal parameter relating toa device-under-test signal input from the terminal of the device undertest to said port.
 12. The network analyzer according to claim 3comprising: an input signal measurer that measures an input signalparameter relating to an input signal input to the device under testbefore the measuring system error factor is generated; a plurality ofports that are connected to a terminal of the device under test, andoutput the input signal; and a device-under-test signal measurer thatmeasures a device-under-test signal parameter relating to adevice-under-test signal input from the terminal of the device undertest to said port.
 13. The network analyzer according to claim 10comprising: an input signal measurer that measures an input signalparameter relating to an input signal input to the device under testbefore the measuring system error factor is generated; a plurality ofports that are connected to a terminal of the device under test, andoutput the input signal; and a device-under-test signal measurer thatmeasures a device-under-test signal parameter relating to adevice-under-test signal input from the terminal of the device undertest to said port.
 14. The network analyzer according to claim 11,wherein said correction coefficient outputter acquires the firstcoefficients and second coefficients of said correction frequencyconverting element according to a ratio of the input signal parametermeasured by said input signal measurer and the device-under-test signalparameter measured by said device-under-test signal measurer.
 15. Thenetwork analyzer according to claim 12, wherein said correctioncoefficient outputter acquires the first coefficients and secondcoefficients of said correction frequency converting element accordingto a ratio of the input signal parameter measured by said input signalmeasurer and the device-under-test signal parameter measured by saiddevice-under-test signal measurer.
 16. The network analyzer according toclaim 13, wherein said correction coefficient outputter acquires thefirst coefficients and second coefficients of said correction frequencyconverting element according to a ratio of the input signal parametermeasured by said input signal measurer and the device-under-test signalparameter measured by said device-under-test signal measurer.
 17. Thenetwork analyzer according to claim 11, wherein said transmissiontracking error acquirer acquires the transmission tracking error basedon a ratio of error factors generated in a passage from thedevice-under-test signal being output from the terminal of the deviceunder test without the frequency conversion to the device-under-testsignal being received by said device-under-test signal measurer.
 18. Thenetwork analyzer according to claim 12, wherein said transmissiontracking error acquirer acquires the transmission tracking error basedon a ratio of error factors generated in a passage from thedevice-under-test signal being output from the terminal of the deviceunder test without the frequency conversion to the device-under-testsignal being received by said device-under-test signal measurer.
 19. Thenetwork analyzer according to claim 13, wherein said transmissiontracking error acquirer acquires the transmission tracking error basedon a ratio of error factors generated in a passage from thedevice-under-test signal being output from the terminal of the deviceunder test without the frequency conversion to the device-under-testsignal being received by said device-under-test signal measurer.